The present invention relates to a high-pressure hot separator for the separation of an overhead product from a process of high-pressure hydrogenation of coals, tars, crude oils, whose distillation and extraction products or similar carbon-containing feedstock such as heavy oils, low-temperature carbonization oils, extracts of heavy oil sands and the like, which is downstream from the bottom phase reactors of the high-pressure hydrogenation. The overhead product is separated into a gas/vapor phase and a bottom product. The separator is constructed from a vertically erected cylindrical pressure vessel jacket (11) with an upper cover (12) and a lower cover or bottom (13), an inside adjacent thermal insulation (14), a cylindrical wall insert (18), which changes into a lower tapering part (18a), with product intake pipe (1) in the pressure vessel, output connecting piece (3) for the gas/vapor phase from the pressure vessel, bottom discharge connecting piece (5) and a cooling circuit provided in wall insert (18), (18a) for indirect cooling.
Hot separators, as they are known for example in units for liquefying coal hydrogenation, consist of compression-proof vessels, which contain inserts cooled by pipe coils, to facilitate the separation of a liquid phase with liquid level in the lower vessel part and to prevent the less volatile stock, containing the separated even solid and ash components, from coking on the hot separator wall despite the high temperatures prevailing in the hot separator. The lower cooled insert is usually designed as a hopper by which the nonvolatile portions are removed. In practical operation it has been shown that despite the cooling of the lower insert by pipe coils, problems occur due to coking which causes the irregular running of the separator and even interruptions of operations (cf. "Die katalytische Druckhydrierung von Kohlen, Teeren and Mineraloelen [The Catalytic Pressure Hydrogenation of Coals, Tars and Crude Oils], Springer-Verlag, Berlin/Goettingen/Heidelberg, 1950, page 243 ff).
Usually hot separators are built for the initially mentioned use range, for which a pressure range up to about 1000 bars, preferably 150-500 bars, is suitable, in a finally geometrically and structurally fixed vessel form corresponding to the requirements for high and ultrahigh pressure standards.
With serious process-side mass flow changes, as they occur, for example, in the use of feedstocks other than grades of coal or heavy oils suitable for the high-pressure hydrogenation, for example, in the hydrogenation of extracts of heavy oil sands or tar sands, which are distinguished, i.e., by considerable contents of aluminum oxide from clays and which as ash-forming components pass into the overhead product of the bottom phase hydrogenation and thus into the hot separator, in a fixed vessel form, which because of the design for the ultrahigh pressures represent very expensive equipment, the degree of separation can considerably worsen. With such high-pressure vessels, geometric and structural changes to match the changed feedstocks and changed operating conditions and to optimize the degree of separation lead to additional costs.
From these circumstances the object of providing for a hot separator, which is determined in its geometry basically by the requirement, which follows from the use in the high-pressure and ultrahigh pressure range, of an optimizable separation function having a comparatively small expense follows.
An object of improving the separation capability of the known hot separator designs, also becomes evident by the fact that at least two hot separators, connected behind one another, have been used in a process for the production of liquid fuels by catalytic pressure hydrogenation in a bottom phase hydrogenation of heavy oils or oil residues and a directly coupled gas phase hydrogenation (cf. DE-PS 933 826).
These objects are achieved with the present invention, which consists in the fact that in the gas/vapor space of the hot separator there is installed a cyclone separator (4) with an connecting piece (2) for the tangential intake of a gas/vapor phase containing liquid components with solid content, a cylindrical section (4a) as well as a lower conical section (4b), a shielding cone (19) placed in the cylindrical or conical section in the area of the axis, a central pipe (4c) placed axially symmetrically for upward removal of the gas/vapor phase freed from the liquid parts, and central pipe (4c) reaches beyond the area of the intake connecting piece (2) downward into the cyclone separator and in the upward direction is connected to the output connecting piece of the gas/vapor phase from the high-pressure vessel.
A patent publication is known with respect to the related art, in which with the presence of several reactor stages it is indicated as suitable to provide at the head of each reactor an inside cyclone for retaining larger catalyst particles. The further separation of the catalyst particles is suitably to take place under process pressure by a cyclone, which is placed within the hot separator downstream from the hydrogenation reactor (cf. DE 26 46 605 C 2).
Further, DE 34 05 730 A 1 is known, in which a separator for flash evaporators of coal hydrogenation units as well as a process are described, in which the suspension from the pressure hydrogenation is expanded to slight pressures in one or more stages, before the suspension is fed to the separator. The separator exhibits a cyclone-like design.
A high-grade separation function in processes and feedstocks of the type as they are applied or used in the high-pressure hot separator according to the invention is not specified in the related art, but is essential because the bottom phase hydrogenation as a rule for recovery of products, which meet the reformer feedstock specifications, is immediately downstream from a so-called gas phase hydrogenation, after the residue phase to be separated in the hot separator is removed. An insufficient separation function would immediately become apparent in a pressure loss in the gas phase hydrogenation taking place in a fixed-bed catalyst, by the unseparated liquid particles entrained in the gas/vapor phase and solid residues and ash-forming components contained in the particles being precipitated on the fixed-bed catalyst and would block it.
Cyclone separator (4) installed in the interior of the hot separator according to the invention is a pure flow device and need not be designed for high pressure. Cyclone separator (4) can be calculated and be optimally designed according to existing process conditions and requirements.
A suitable configuration of the high-pressure hot separator consists in the intake connecting piece of the cyclone separator being provided with a scrubbing device consisting of a scrubber nozzle and feed pipe for scrubbing liquid. In this way, the formation of solid deposits in the area of the intake connecting piece of the cyclone separator can be effectively prevented.
The product intake pipe for the overhead product from the bottom phase reactor is suitably designed so that it ends in the gas/vapor space of the pressure vessel above the liquid level formed by the bottom product in the hot separator and is adapted to the form of the cylindrical wall insert so that basically a downward flow is directed tangentially obliquely against the wall insert.
It can be suitable to immerse the discharge of the bottom product from the cyclone separator by a discharge pipe under the liquid level in the hot separator. In the actual design, attention is to be given to the fact that a great partial vacuum may prevail in each cyclone in the axis. With great density in the high-pressure hot separator corresponding to the higher pressure the vacuum is much greater than is customary in normal uses. According to calculations, the cyclone would fill up from below. The shielding cone provided in the cylindrical part in the area of the axis serves to avoid this difficulty. By suitable dimensioning of the discharge pipe, it is possible to prevent the pipe from being stopped up by solid deposits.
For the above reasons another suitable embodiment provides that the bottom product is removed from the conical part of the cyclone separator by a pipe connected to a flash pot downstream from the hot separator.
But in the above-mentioned configuration the conical part of the cyclone separator can also be made closed downward. In this case, the main part of the condensed bottom product, as before, is removed by the bottom discharge connecting piece in the lower cover of the hot separator. Only the amount of liquid separated in cyclone separator (4) is removed from the high-pressure vessel by a separate pipe run, for example, through the output connecting piece for the gas/vapor phase.
The high-pressure hot separator for the above-mentioned reasons is suitably equipped with a level control measurement. The latter can be made as a differential pressure measurement, and hydrogen is bubbled through by two separate pipes, the so-called zero pipe and a pipe reaching into the bottom of the conical part of the cyclone and the differential pressure to be measured is registered on the basis of the height of the level in the hydrogen feed pipes.
The hydrogen intake pipes for the level measurement as well as pipe (20) for the removal of the bottom product from the conical part of the cyclone separator are run, e.g., from the high-pressure vessel through the special convex seal on the output connecting piece of the gas/vapor phase, as it is represented in detail in FIG. 4.
By direct introduction through the intake pipe (8) of hydrogen-containing gases into the liquid level of the bottom product in lower conical separator part (18a), a hydrogen depletion, which can lead to an additional coke formation and deposit, is counteracted.
Vertical cylindrical wall insert (18) of the high-pressure hot separator, according to a suitable configuration, by the conical part turns into bottom discharge connecting piece (5) in the bottom of the pressure vessel.
The cylindrical wall insert will be a component of a cooling circuit for indirect cooling by pipes, run through the upper or lower cover of the pressure vessel, for feeding and discharge of coolant, and the wall insert can be made of finned pipes as they are known in boiler technology. But the wall insert can also consist of ordinary pipes with flanges welded in between.
By the tangential flow with the overhead product of the bottom phase hydrogenation on the vessel wall a certain preseparation is achieved and the mode of operation of the hot separator as a gravity separator is improved in that the liquid level in the hot separator is not unnecessarily raised again by condensed liquid portions falling from a certain height.
The present high-pressure hot separator in cases of especially wear-intensive mineral components in the overhead product of the bottom phase hydrogenation, such as, e.g., aluminum oxide from clays, as they occur in the use of oils from tar sands on especially wear-stressed zones or on the entire inner surface can be equipped with a wear-armoring, for example made of tungsten carbide or wear-resistant ceramic coatings.